Organic-inorganic nanocomposite containing Keggin polyoxometalate, H 3PMo12O40 has been designed and synthesized by sol-gel method. The embedded polyoxometalate has been characterized by various physico-chemical techniques like TGA, SEM, TEM, cyclic voltammetry and IR, UV-visible and electrochemical impedance spectroscopy. Detailed electrochemical studies have been carried out. Effects of pH, potential variation and stability have been studied. The prepared organic-inorganic nanocomposite has been employed for the reduction of nitrite in sulphuric acid medium by using cyclic voltammetric and chronoamperometric methods. The electrode response has been found to be linear for NO2 within the concentration range of 8.4 × 10-5 M to 15 × 10-3 M. The composite electrode has a sensitivity of 4.5 μA mM-1.